Hereinafter, a conventional speaker system is described. A conventional speaker system includes an enclosure (cabinet), a speaker unit, and an activated carbon elastic sheet. The enclosure has an air gap inside thereof. The speaker unit and the activated carbon elastic sheet are housed in the air gap. As the activated carbon elastic sheet, an activated carbon fiber layer obtained by forming activated carbon into a sheet-shaped (rectangular parallelepiped shaped) lump is used.
Activated carbon has extremely many fine pores. The fine pores improve a sound pressure level of a low sound. However, when the fine pores of the activated carbon adsorb water vapor, the sound pressure level of a low sound is reduced. Thus, in order to suppress moisture absorption by activated carbon, a method for forming a resin-impregnated layer by impregnating the front and back sides of the activated carbon fiber layer with a moisture-resistant resin, has been thought. That is to say, an activated carbon elastic sheet having a structure in which an activated carbon fiber layer (activated carbon) is sandwiched between resin-impregnated layers (activated carbon which has been impregnated with resin) is used.
Note here that information on prior art documents relating to the invention of this application include, for example, PTL 1.